This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 5 |
| 3 | 40 |
| 4 | 285 |
| 5 | 2000 |
| 6 | 14005 |
| 7 | 98040 |
| 8 | 686285 |
| 9 | 4804000 |
| 10 | 33628005 |
| 11 | 235396040 |
| 12 | 1647772285 |
| 13 | 11534406000 |
| 14 | 80740842005 |
| 15 | 565185894040 |
| 16 | 3956301258285 |
| 17 | 27694108808000 |
| 18 | 193858761656005 |
| 19 | 1357011331592040 |
| 20 | 9499079321144285 |